Jonathan Camilleri

Brief Biography

Whilst growing up, I always had an interest in the physical sciences, with electronics and outer space being of a particular interest to me than the rest of the topics I had ever studied before. For that reason I did an Bachelor degree in Electrical and Electronic Engineering at the University of Malta, where I am from. During my four years of undergraduate study, I also went on a semester long exchange at the University of Nottingham, where I feel I learnt how to deal with being in situations outside of my comfort zone, as it was my first time living abrad in a foreign country.

After graduating with Honours in Electrical and Electronics Engineering, my interests in physics and outer space motivated me to move to the University of Surrey in Guildford, where I studied and obtained a Master of Science in Space Engineering.

following my Master’s degree, I realised that the Space Engineering field was too interesting to not follow it. Hence, that was when I decided to start a Doctoral programme at the University of Birmingham, as I felt that the design of what can be future space hardware, would be an invaluable experience.

Research Interests

My research interests are fairly broad. Mostly I am interested in space exploration, and new technologies that could make said space exploration, both unmanned and manned, easier. Specifically, because of the electronics engineer in me, I am mostly interested in instrumentation, sensor design and data acquisition methods. However, I am also very fascinated by spacecraft orbital and attitude behaviour and control and spacecraft operations.

Current Project

The ionosphere and ionospheric plasma were investigated and to determine a suitable method of taking in-situ measurements of electron density from the topside ionosphere (F-region) for the purpose of ionospheric modelling and space weather forecasting. It was identified that the best method to do this was by having a specialised instrument on a small, specialised PQ class spacecraft orbiting in the F-region of the ionosphere, or as a secondary payload on larger spacecraft.

Three different methods of ionospheric plasma electron density measurement have been investigated, these being the use of a Langmuir’s probe, a Retarding Potential Analyser and a Plasma Impedance Probe were considered. After a thorough investigation of these methods, the Impedance probe was considered as the best instrument to be sued for such electron density measurement, by taking measurements of the plasma impedance at different frequencies. These measurements are to be used to determine the plasma’s Z(ω)-ω characteristic, from which the UHR frequency could be obtained. In turn, the UHR frequency could be used to determine the electron density.

As a PQ class spacecraft was determined to be the ideal platform for the instrument, it was determined that the instrument should fit on one 5 × 5 cm PCB, due to the restrictions in physical space and power consumption. The instrument architecture is to be in three parts, an analogue front end, a signal generation block and a digital back end. The instrument would also make use of an antenna mounted on the spacecraft, which could be either a dedicated antenna, or time shared between the communications of the spacecraft as as long as the antenna has a 0 Ω impedance for the desired range of frequencies of 100 kHz to 10 MHz.

Two different signals are being investigated to be transmitted through the antenna to excite the ionospheric plasma for impedance measurements. The first is a frequency sweep with impedance measurements being taken for each frequency, whilst the second is the transmission of a PN signal to obtain a “snapshot” like sample of the ionospheric plasma impedance.

Testing of the instrument is to be done in a TVC available at the University of Birmingham Physics Department. A plasma generator is required to generate the free electrons to simulate the ionospheric plasma environment in the TVC. Such a generator is to be implemented using a thermal cathode dispenser. Also a Langmuir probe is required inside the TVC to obtain control measurements of the plasma’s I-V characteristic and eventually the electron density, for comparison with the measurements obtained from the impedance probe instrument.

Future work includes the design, prototyping, assembly and initial testing of the ImP instrument; the development, assembly and testing of the Plasma Generator to simulate the ionospheric environment inside the TVC and the development, assembly and testing of a Langmuir Probe to provide control readings of the ionospheric plasma impedance inside the TVC. Also an interface in LabVIEW is to be programmed to ensure control of the Plasma Generator can be done via a computer, and that readings from the Langmuir Probe can be monitored and logged on a computer. This is to be followed by the testing of the two different modes of operation of the ImP instrument, these being the Frequency Sweep and the PN signal techniques for impedance measurement.